The rail line is a 10.5-mile light-rail transit extension, which will travel through the city of Aurora and one small section of the city and county of Denver. The I-225 Corridor will connect the existing Southeast Light Rail Nine Mile Station with the planned East Rail Line's Peoria/Smith Station and will include eight stations.

The line is being constructed as part of a combined project with the Colorado Department of Transportation (CDOT) on the expansion of lanes on the I-225 highway. This allows RTD and CDOT to complete the rail line and highway expansions by sharing construction resources.

The first segment of the line, from Nine Mile to Iliff, began construction in May 2012.

Kiewit Infrastructure Co. was awarded a contract to complete the I-225 light-rail line to Peoria by November 2015, which would allow the line to open in mid-2016 after six months of testing.